Percussive tool



Patented Oct. 28, 1930 WIILEIAN A.V sMrrn, lsR., or EASTON; RENNsYLVaNrA, lAND .'r'osErH lI. HULSEIZER; or srEwaRTsvrLLE, AND GEORGE EUEHRER, or. PHILLIPS-BURG, NEW JERSEY, As.- sIGNoRs To INGERsoLL-RAND COMPANY, or JERSEY CITY, NEW JERSEY, A Conro- RATIONOF NEW'HERSEYY Y rERoUssIVE'aooL npnwnmn inea November 27, 1929. serial No. alfiere.` u

`This invention relates' to percussivetools, but more particularly to fluid'ractuated per- Vcussive tools of the valveless type in-which the distribution of pressure fluid is effected by the hammer piston.Vv l g The objects ofthe invention are to increase the efficiency Vof tools of this type, to simplifythe construction and' to obtain a-powerful blow of the hammer piston against the working implement with'a minimum consumption of pressure fluid.v Y l' Other objects'will be in partV obvious and in part pointed out hereinafter.

In the drawings `illustrating the invention and in which vsimilar reference characters refer to similar parts,

Figure 1 is a sectional elevation constructed in accordance with the practice of the inven tion and'showing the hammer piston at the beginning of its stroke, and Figure 2 is a similar View showing-the hamn mer piston at the beginning of its return stroke. j

Referring more particularly to the drawings, A designates a cylinder of a percussive tool having a piston chamber B inthe rearward end of which is an annular groove C. The cylinder A is provided with front and rear exhaust ports D andE respectively which are controlled by a hammer piston F reciprocable in the piston chamber B.

Atthefront end of the cylinder A is disposeda head G to `form a closure for the front.

end of the piston chamber B and said head is providedwith a bore H to Vact as a guide for a working implement J which'extends into theV lfront end of the piston chamber B to receive the blows of the hammer piston.

`Atthe rearend of the cylinder A is disposed a back head K which may be secured fiXedlyto the cylinder A in any suitable manner. The back head K serves as a casing for a throttle valve L which; as indicated, may

t be of' the rotary type for controlling the admission or" pressure fluid into lthe-tool. The throttle valveL has a central chamber O into which pressure fluid maybe constantly admitted from a suitable source of supply, and in the wall of the throttle valve L is a port P which registers` with a the back head K( i 4 The piston F `is of cup-shape and has a central recess which serves as aypressure chamberv B. The piston is otherwise imperorate and is therefore sufficiently durable and strong to withstand the heavy jars and passage Q, also in "shocks to which it is subjected upon impact against thel working implement J. n

Extending into the pressure chamber R is an inlet plug S carrying'at its rear end a lateral flange T which ,lies within an enlarged bore U in-'the Vrear end of the'cylinder and forms a seat for the back head'K.A The plug Sis provided with a supply pacsage V into which the passage Q, opens. The supply passage V extends forwardlythrough the plug S and opens into the pressure chamber E so that when the throttle valve L is Y opened pressure fluid will be' constantly admitted into ,the pressure chamber R to act against a pres-sure surface W at the front end of thepressure chamber R tending to actuate the piston F forwardly.'

In the inlet plug S and at a point intermediate theends of the supply passage V wherewith it communicates is a supply port X which opens into the periphery of the plug S and inthe piston F is an annular groove Y which is adapted to afford communication between the supply port X anda neel; Z in the periphery of the plug S and preferably adjacent the flange T.

Y The annular groove Y also serves to establish communication between the pressure chamber R and a Vfront inletpassage which extends through the plug S and through the cylinder 'A to the front end of the piston chamber B. The inlet opening or port c of the inlet passage b is preferably locatedvonly 'slightly rearwardly lof the front end of the plug S'. t

The operation of the tool is asffollows: With the piston in the rearmost position illustrated in Figure l, pressurefluid flowing through the supply passage V will pass through the supply port X into and through lthe annular groove Y." Fromv the groove Y the pressure fluid passes around theneck Z into fthefrear' end'V of the piston chamber B Cil to assist the pressure fluid acting against the pressure surface W to drive the piston F forwardly against the working implement.

Shortly after the piston has started on its forward stroke, communication between the annular groove Yin the piston and the neck Z in the plug S will be cut-0H. This cut-off of pressure iuid to the rear end of the piston chamber will occur before the piston uncovers the exhaust port E. The pressure fluid acting against the rear end the piston as well as that acting against the pressure surface W will then act expan-sively-to drive the piston forwardly.

Immediately prior to the delivery of the blow of the hammer piston against the worlring implement the rear end of the piston will uncoverthe exhaust port E and the pressure fluidI will then be exhausted from the rear end of the piston chamber B to the atmoshfere. At the sametime the annular groove in the piston will uncover the front inlet passage Z). Pressure iiuid will then How from the pressure chain-ber R through the inlet passage b into the front end of the piston chamber B to act against the piston F for driving said piston rearwardly against the opposing pressure acting' against the pressure surface W. y

As the piston F proceeds rearwardly the front exhaust port Dwill be uncovered thereby and the pressure fluid will be exhausted from the front end of the piston chamber. At the same time pressure fluid will be admitted into the rear end of the piston chamber toV again assist that acting against the pressure surface W for driving the piston E forwardly.

During the rearward stroke of the piston, said piston will be actuated throughout a portion of itsr stroke by the expansiveaction of the pressure iiuid. This is due tothe fact that communication will be cut-off between the pressure chamber R and the inlet passage b before the exhaust port D will be uncovered by the piston.

As will be observed, by providing the rear end of the piston chamber B with the annular groove C an ample charge of pressure iiuid may be introduced into the rearward end of the piston chamber to assure a powerful blow of the piston against the working im.- plement. This groove C also serves as a vclearance pocket during the rearward stroke of the piston since, as will be observed, the rear exhaust port E will be covered by the piston shortly after the piston starts. on its rearward stroke and any air in the back end of the piston chamber will therefore not be compressed to a sufficiently high value to retard the return movement of the piston..

We claim: l Y l. In a fluid actuated percussive tool., a cylinder having exhaust ports, a plug extending into the cylinder and-having a supply passage and a supply port leading from the supply passage to the periphery of the plug, an inlet passage in the plug and the cylinder for conveying pressure fluid to one end of the cylinder, and a piston in the cylinder into which the plug extends and adapted to control coinmunication between the supply port and one end of the cylinder for driving the piston in one direction and between tl'iesupply'passage and the inlet passage for actuating the piston in the opposite direction.

2. In a Huid actuated percussiv'e tool, a: cylinderhaving exhaust ports, a plug extending into the cylinder and having a supply passage and' a supply port leading from the supply passage to thel periphery of the plug, an inlet passage in the plug and the cylinder for conveying pressure fluid to the front end of the cylindeiu a cup-shaped imperforate piston having a constant pressure chamber into which the plug extends, and an annular groove inthe piston to establish communication between the supply port and the rea-r end of the cylinder and between the supply passage and the inlet passage.

3. ln a iiuid actuated percussive tool, a cylinder having exhaust ports, a piston in the cylinder havin-g a. pressureA chamber therein, an inlet plug extending into the pressure chamber and having a supply passage to constantly admit pressure fluid into the chainber, an inlet passage extending through the plug and' the cylinder to the front end of the cyli1-ider,.a supply port in theplug and' in constant communication with the supply passage, and an annulary groove the' piston' to establish communication between the pressure chamber and the inlet passage in one position of the piston and between theI supply port. and the rearv end of the. cylinder in. another position of the piston.A

el. Inl a Huid actuated percussive tool, a cylinder having exhaust ports, a piston in: the cylinder having a pressure chamberv therein, a plug; extending into the cylinder' and having a supply passage for constantly admitting pressure fluid into the chamber, a front inlet passage extending through the plug and the cylinder to the front end of the cylinder', a supply port in the plug and in constant corinm'unication with the supply passage', a neck on the plug; andy anI annular groove in the piston to establish communication between the pressure chamber and the neck to supply pressure fluid to the rear end of the cylinder and to establish communication between the pressure chamber andthe fro-nt inlet passage.

ln testimony whereof we have signed this specification.

WILLIAM A. SMITH, Sn; JOSEPH I. HULSHIZER.. GEORGE H.` FUEHRER. 

